Pneumatic fire alarm system



April 30, 1968 J. E. HOGEL 3,380,430

PNEUMATIC FIRE ALARM SYSTEM Filed May 13, 1966 SOURCE FIB. g INVENTOR. JOSEPH E. HOGEL W 2; yea/W ATTORNEY United States Patent 3,380,430 PNEUMATIC FIRE ALARM SYSTEM Joseph E. Hogel, River Grove, Ill., assignor to Honeywell Inc., Minneapolis, Minn., a corporation of Delaware Filed May 13, 1966, Ser. No. 549,927 7 Claims. (Cl. 116-65) The invention relates generally to pneumatic alarm systems and more particularly to a pneumatic fire alarm system providing supervision of both pressure line breakage and blockage.

Pneumatic fire alarm systems presently experience wide usage in larger installations because of greater operating economy. However, they are generally quite complex from the standpoint of alarm station structure and multiplicity of interconnecting pressure 'lines, and they do not furnish the necessary supervision of both pressure line blockage and breakage.

The pneumatic fire alarm system described herein is a single pipe, continuous bleed system including several manually operable alarm stations that are disposed in different zones or locations within the building that is supervised. The alarm stations are essentially normally closed valves that open to bleed supply air to atmosphere upon manual pull down of the alarm station handle. Each alarm station is adjusted to a different bleed level, and accordingly each alarm station, upon manual pull down, can establish a discrete pressure in the single interconnecting pipe line. A pressure gauge is used as an alarm indicator to sense the pipe line pressure and announce that a particular alarm station in a particular zone has been actuated. Under no-alarm conditions all alarm stations are closed, and the continuous air supply bleeds to atmosphere through a restriction at the end of the pipe line. This continuous bleed configuration enables the system to detect pipe line blockage (line pressure at a maximum) and pipe leakage or breakage (line pressure at zero). A reserve supply provides operating pressure automatically in the event of normal pressure source failure.

In short, the invention provides an extremely simple and economical fire alarm system that is capable of simultaneous supervision of a block or break in the pipe line.

In the drawings:

FIGURE 1 is a schematic representation of the overall system; and

FIGURE 2 is a cross section of alarm station structure.

In FIGURE 1, a pressure source I11 is connected to a conduit 12. Associated with pressure source 11 are a check valve 13 and a storage tank 14. Restrictions 15, 16 are disposed Within conduit 12 as shown, and a zone indicator and alarm 17 is positioned therebetween. Indicator 17 consists of a pressure gauge that is calibrated to provide a readout of no alarm, alarm, alarm location, line breakage or line blockage, corresponding to the pressure sensed in conduit 12. Also located between restrictions 15, 16 are a plurality of alarm stations represented generally by the numeral 18, connected to conduit 12 by individual connecting lines 119.

In FIGURE 2 an alarm station 18 is shown in a detailed cross section. An alarm station housing 33 provides a supporting structure for the operating components of alarm station 18. Connecting line 19 opens into a chamber 21 to provide pressure from conduit 12 to a nozzle 22. Associated with nozzle 22 is a flapper 23 which is suitably secured to the alarm station housing 33 for movement relative to the nozzle 22. A port 27 exhausts the flow that passes through nozzle 22 to atmosphere. Flapper 23 is ground or lapped to provide a smooth and accurate fit with nozzle 22 and is biased against nozzle 22 by a spring 24 and a rigid member 25. Spring 24 is held in place against flapper 23 by an annular threaded member 26 3,380,430 Patented Apr. 30, 1968 which can be adjusted to produce a variable spring load on flapper 23. Rigid member 25 is held against flapper 23 by a slideable handle 31 and is guided by annular threaded member 26. A perforation 32 in handle 31 is adapted to receive fixed member 25 upon movement of handle 31 to its annunciation position.

Nozzle 22 has a large cross sectional area as compared to that of restrictions 15, 16 generally on the order of to 1 or greater. This design provides a force feedback type of operation similar to the one described in US. Patent 3,174,499, issued on Mar. 23, 1965 to Richard C. Mott. Briefly, the effective flapper area exposed to chamber 21 enables the pressure in chamber 21 to exert a relatively large force on flapper 23. When handle 31 is caused to slide to its annunciation position, rigid member 25 moves into perforation 32, leaving spring 24 biased against flapper 23. Spring 24 is adjusted by threaded member 26 to exert a force on flapper 23 that is less than the pressure times area force exerted on the underside of flapper 23. Accordingly, flapper 23 moves away from nozzle 22, allowing part of the pressure in chamber 21 to bleed otf and exhaust through port 27. As pressure within chamber 21 decreases, flapper 23 is partially restored by spring 24 until the feedback pressure in chamber 21 builds up again. Nozzle 23 is quickly stabilized by reason of this balance of forces and a steady pressure is thus established in connecting line 19 and common conduit 12. Adjustment of the spring load by movement of the threaded member 26 results in the establishment of a ditferent steady pressure in common conduit 12. Excellent pressure control is obtained by this large nozzle-flapper configuration.

In overall operation, each of the alarm stations 18 is placed in a different zone or location of the supervised area and adjusted to establish a discrete pressure in the common conduit 12 upon movement of the handle 31 to its annunciation position. Thus, actuation of the handle 31 of a particular alarm station Will establish a particular pressure in conduit 12 that corresponds with a particular building zone,

Under a no-alarm condition, all of the alarm stations 18 are in a closed position. The fluid flow provided by pressure source 11 initially passes through check valve 13 and builds up in storage tank 14. Check valve '13 prevents back flow from occurring. Forward flow continues through restriction 15 and since all alarm stations 18 are closed, the fluid is bled to atmosphere through restriction 16. A steady pressure is thus established in conduit 12 between restrictions 15, 16. Pressure gauge indicator 17 furnishes a calibrated readout for this pressure, indicating a n0- alarm condition.

If alarm conditions exist in a particular zone, pull down of handle 31 of the alarm station located in that zone will cause flapper 23 to move away from nozzle 22, and the controlled bleed-off will begin as described above. This causes a lower steady pressure in conduit 12, and indicator 17 reflects this change in line pressure in the form of a readout showing the alarm and designating its location.

If conduit 12 should become blocked for any reason, this would be shown by indicator 17 in the form of a maximum pressure readout. Similarly, a line leakage or breakage would result in total bleed 011 of the pressure in conduit 12, and indicator 17 would accordingly provide a zero pressure readout. If for some reason the pressure source 11 ceases to operate, the check valve 13 and storage tank 14 would act as a reserve supply by continuing to supply pressure for a period of time.

While I have shown six alarm stations in FIGURE 1, it is evident that any number could be included in the alarm system so long as a suflicient operating pressure is maintained. Similarly, the system described here is operated on air pressure but other fluids could be used to obtain satisfactory operation. It is to be understood that these and other modifications can be made without departing from the scope of my invention, and I wish to be limited only by the scope of the appended claims.

I claim as my invention:

1. An alarm system, comprising:

pressure source means;

conduit means connected to said pressure source means and including a first and a second pressure restriction, said first restriction disposed between said pressure source means and said second restriction with said second restriction being constantly open and bleeding the fluid supplied by said pressure source means to atmosphere;

a plurality of bleed-type alarm stations connected to said conduit means between said first and second restrictions by individual connecting means, each of said alarm stations in non-bleed position under noalarm conditions, each of said alarm stations openable to an adjustable bleed position, and each of said alarm stations adjusted to a diflerent bleed position to establish a discrete pressure in said conduit means upon opening said alarm station to said bleed position;

and alarm indicator means connected between said first and second restrictions for sensing the pressure in said conduit means.

2. The system as defined in claim 1, wherein said pressure source means comprises pressure supply means; pressure storage means disposed between said first retriction and aid pressure supply means; and check valve means disposed between said pressure storage means and said pressure supply means, said check valve means blocking flow from said pressure storage means to said pressure supply means and allowing flow in the opposite direction.

3. The system as defined in claim 1, wherein each alarm station comprises means housing a cooperating nozzle and flapper, each of said nozzles communicating with an individual connecting means, said flapper biased against said nozzle by a rigid member and an adjustable resilient member, adjustable means for holding said resilient member against said flapper and for adjusting the force exerted by said resilient member on said flapper, said rigid member adapted to be released from a fixed position against said flapper.

4. The system as defined in claim 3, wherein the size of said nozzle is large compared to the size of said restrictions to effect a force balance type of operation at each of said alarm stations when actuated.

5. The system as defined in claim 3, wherein said rigid member is held in fixed position against said flapper by a moveable handle, said handle adapted to release said rigid member from its fixed position upon manual movement.

6. The system as defined in claim 3, wherein said resilient member comprises spring means, and said adjustable means comprises an annular threaded member adapted to screw into said housing means.

7. The system as defined in claim 1, wherein said alarm indicator means comprises a pressure gauge including calibrations of no alarm, alarm, alarm location, line breakage and line blockage.

References Cited UNITED STATES PATENTS 3,223,105 12/1965 Hogel 137-85 ALAN COHAN, Primary Examiner. 

1. AN ALARM SYSTEM, COMPRISING: PRESSURE SOURCE MEANS; CONDUIT MEANS CONNECTED TO SAID PRESSURE SOURCE MEANS AND INCLUDING A FIRST AND A SECOND PRESSURE RESTRICTION, SAID FIRST RESTRICTION DISPOSED BETWEEN SAID PRESSURE SOURCE MEANS AND SAID SECOND RESTRICTION WITH SAID SECOND RESTRICTION BEING CONSTANTLY OPEN AND BLEEDING THE FLUID SUPPLIED BY SAID PRESSURE SOURCE MEANS TO ATMOSPHERE; A PLURALITY OF BLEED-TYPE ALARM STATIONS CONNECTED TO SAID CONDUIT MEANS BETWEEN SAID FIRST AND SECOND RESTRICTIONS BY INDIVIDUAL CONNECTING MEANS, EACH OF SAID ALARM STATIONS IN NON-BLEED POSITION UNDER NOALARM CONDITIONS, EACH OF SAID ALARM STATIONS OPENABLE TO AN ADJUSTABLE BLEED POSITION, AND EACH OF SAID ALARM STATIONS ADJUSTED TO A DIFFERENT BLEED POSITION TO ESTABLISH A DISCRETE PRESSURE IN SAID CONDUIT MEANS UPON OPENING SAID ALARM STATION TO SAID BLEED POSITION; AND ALARM INDICATOR MEANS CONNECTED BETWEEN SAID FIRST AND SECOND RESTRICTIONS FOR SENSING THE PRESSURE IN SAID CONDUIT MEANS. 